I tried this out and it cleared my tank up some...but not enough to suggest it to others...the people on the forum said it worked for them so...I also hear that water changes dont work because essentially your adding back what the GW is feeding off of, the nutrients that are in your water and such. Im battling with this also and its been about a month or so and am going to try a DIY diatom filter....but if yuo can get it cleared without spending lots of money....id be GLAD to hear it!